Greenpois0n RC5 can jailbreak i Phone 4, i Phone 3GS untethered running i OS 4.2.1 firmware.
Greenpois0n untethered jailbreak does NOT require SHSH blobs for i OS 4.2b3.
If you’re already running i OS 4.2.1, skip to the next step (Make sure you read the imporant part above).
Connect your i Phone 4 or i Phone 3GS to your computer via USB cable and restore i OS 4.2.1. Follow the onscreen instructions to put i Phone into DFU mode.
The latest version of Greenpois0n has been released for download, it offers an untethered jailbreak for i OS 4.2.1.
The Mac and Windows release come as Green Pois0n 1.0 RC5, with a Linux version due out soon.
option as shown in the screenshot below: Once you have successfully booted your device into jailbroken state, you can use Cydia and SSH into your device easily.
Follow our how to jailbreak i OS 4.2.1 untethered with Green Pois0n 1.0 RC5 guide if you need assistance. If you are currently using a tethered jailbreak like redsn0w, you should restore before jailbreaking again with Green Pois0n 1.0 RC5.Now i Phone 4 users who preserved their baseband to can unlock using the following guide: How to Unlock i Phone 4 baseband with Ultra Sn0w You can follow us on Twitter, Join us at Facebook, and also Subscribed to RSS Feed to receive latest updates.has released an updated version of Redsn0w (v0.9.6b4) to jailbreak i OS 4.2.1 on i Phone 4/3GS/3G, i Pod Touch 4G/3G/2G & i Pad (Wifi 3G).Held the sleep button nogood, held the home button while plugging in to usb still nothing.Sometimes, when trying to jailbreak your i Phone, i Pad or i Pod Touch you might run into some unexpected errors that can leave your device stuck in either DFU or Recovery mode.